Why Are There 5,280 Feet in a Mile?

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iStock

Why are there 5,280 feet in a mile, and why are nautical miles different from the statute miles we use on land? Why do we buy milk and gasoline by the gallon? Where does the abbreviation "lb" come from? Let's take a look at the origins of a few units of measure we use every day.

The Mile

The basic concept of the mile originated in Roman times. The Romans used a unit of distance called the mille passum, which literally translated into "a thousand paces." Since each pace was considered to be five Roman feet—which were a bit shorter than our modern feet—the mile ended up being 5,000 Roman feet, or roughly 4,850 of our modern feet.

If the mile originated with 5,000 Roman feet, how did we end up with a mile that is 5,280 feet? Blame the furlong. The furlong wasn't always just an arcane unit of measure that horseracing fans gabbed about; it once had significance as the length of the furrow a team of oxen could plow in a day. In 1592, Parliament set about determining the length of the mile and decided that each one should be made up of eight furlongs. Since a furlong was 660 feet, we ended up with a 5,280-foot mile.

The Nautical Mile

So if the statute mile is the result of Roman influences and plowing oxen, where did the nautical mile get its start? Strap on your high school geometry helmet for this one. Each nautical mile originally referred to one minute of arc along a meridian around the Earth. Think of a meridian around the Earth as being made up of 360 degrees, and each of those degrees consists of 60 minutes of arc. Each of these minutes of arc is then 1/21,600th of the distance around the earth. Thus, a nautical mile is 6,076 feet.

The Acre

Like the mile, the acre owes its existence to the concept of the furlong. Remember that a furlong was considered to be the length of a furrow a team of oxen could plow in one day without resting. An acre—which gets its name from an Old English word meaning "open field"—was originally the amount of land that a single farmer with a single ox could plow in one day. Over time, the old Saxon inhabitants of England established that this area was equivalent to a long, thin strip of land one furlong in length and one chain—an old unit of length equivalent to 66 feet—wide. That's how we ended up with an acre that's equivalent to 43,560 square feet.

The Foot

As the name implies, scholars think that the foot was actually based on the length of the human foot. The Romans had a unit of measure called a pes that was made up of twelve smaller units called unciae. The Roman pes was a smidge shorter than our foot—it came in at around 11.6 inches—and similar Old English units based on the length of people's feet were also a bit shorter than our 12-inch foot. The 12-inch foot didn't become a common unit of measurement until the reign of Henry I of England during the early 12th century, which has led some scholars to believe it was standardized to correspond to the 12-inch foot of the king.

The Gallon

The gallon we use for our liquids comes from the Roman word galeta, which meant "a pailful." There have been a number of very different gallon units over the years, but the gallon we use in the United States is probably based on what was once known as the "wine gallon" or Queen Anne's gallon, which was named for the reigning monarch when it was standardized in 1707. The wine gallon corresponded to a vessel that was designed to hold exactly eight troy pounds of wine.

The Pound

Like several other units, the pound has Roman roots. It's descended from a roman unit called the libra. That explains the "lb" abbreviation for the pound, and the word "pound" itself comes from the Latin pondo, for "weight." The avoirdupois pounds we use today have been around since the early 14th century, when English merchants invented the measurement in order to sell goods by weight rather than volume. They based their new unit of measure as being equivalent to 7000 grains, an existing unit, and then divided each 7000-grain avoirdupois pound into 16 ounces.

Horsepower

Early 18th-century steam engine entrepreneurs needed a way to express how powerful their machines were, and the industrious James Watt hit on a funny idea for comparing engines to horses. Watt studied horses and found that the average harnessed equine worker could lift 550 pounds at a clip of roughly one foot per second, which equated to 33,000 foot-pounds of work per minute.

Not all scholars believe that Watt arrived at his measurement so scientifically, though. One common story claims that Watt actually did his early tests with ponies, not horses. He found that ponies could do 22,000 foot-pounds of work per minute and figured that horses were half again stronger than ponies, so he got the ballpark figure of 33,000 foot-pounds of work per minute.

What Is the Kitchen Like on the International Space Station?

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iStock/Elen11

Clayton C. Anderson:

The International Space Station (ISS) does not really have a "kitchen" as many of us here on Earth might relate to. But, there is an area called the "galley" which serves the purpose of allowing for food preparation and consumption. I believe the term "galley" comes from the military, and it was used specifically in the space shuttle program. I guess it carried over to the ISS.

The Russian segment had the ONLY galley when I flew in 2007. There was a table for three, and the galley consisted of a water system—allowing us to hydrate our food packages (as needed) with warm (tepid) or hot (extremely) water—and a food warmer. The food warmer designed by the Russians was strictly used for their cans of food (about the size of a can of cat food in America). The U.S. developed a second food warmer (shaped like a briefcase) that we could use to heat the more "flexibly packaged" foodstuffs (packets) sent from America.

Later in the ISS lifetime, a second galley area was provided in the U.S. segment. It is positioned in Node 1 (Unity) and a table is also available there for the astronauts' dining pleasures. Apparently, it was added because of the increasing crew size experienced these days (6), to have more options. During my brief visit to ISS in 2010 (12 days or so) as a Discovery crewmember, I found the mealtimes to be much more segregated than when I spent five months on board. The Russians ate in the Russian segment. The shuttle astronauts ate in the shuttle. The U.S. ISS astronauts ate in Node 1, but often at totally different times. While we did have a combined dinner in Node 1 during STS-131 (with the Expedition 23 crew), this is one of the perceived negatives of the "multiple-galley" scenario. My long duration stint on ISS was highlighted by the fact that Fyodor Yurchikhin, Oleg Kotov, and I had every single meal together. The fellowship we—or at least I—experienced during those meals is something I will never, ever forget. We laughed, we argued, we celebrated, we mourned …, all around our zero-gravity "dinner table." Awesome stuff!

This post originally appeared on Quora. Click here to view.

Clayton "Astro Clay" Anderson is an astronaut, motivational speaker, author, and STEAM education advocate.

His award-winning book The Ordinary Spaceman, Astronaut Edition Fisher Space Pen, and new children's books A is for Astronaut; Blasting Through the Alphabet and It's a Question of Space: An Ordinary Astronaut's Answers to Sometimes Extraordinary Questions are available at www.AstroClay.com. For speaking events www.AstronautClayAnderson.com. Follow @Astro_Clay #WeBelieveInAstronauts

What Do the Numbers and Letters on a Boarding Pass Mean?

iStock.com/Laurence Dutton
iStock.com/Laurence Dutton

Picture this: You're about to embark on a vacation or business trip, and you have to fly to reach your destination. You get to the airport, make it through the security checkpoint, and breathe a sigh of relief. What do you do next? After putting your shoes back on, you'll probably look at your boarding pass to double-check your gate number and boarding time. You might scan the information screen for your flight number to see if your plane will arrive on schedule, and at some point before boarding, you'll also probably check your zone and seat numbers.

Aside from these key nuggets of information, the other letters and numbers on your boarding pass might seem like gobbledygook. If you find this layout confusing, you're not the only one. Designer and creative director Tyler Thompson once commented that it was almost as if "someone put on a blindfold, drank a fifth of whiskey, spun around 100 times, got kicked in the face by a mule … and then just started puking numbers and letters onto the boarding pass at random."

Of course, these seemingly secret codes aren't exactly secret, and they aren't random either. So let's break it down, starting with the six-character code you'll see somewhere on your boarding pass. This is your Passenger Name Reference (or PNR for short). On some boarding passes—like the one shown below—it may be referred to as a record locator or reservation code.

A boarding pass
Piergiuliano Chesi, Wikimedia Commons // Public domain

These alphanumeric codes are randomly generated, but they're also unique to your personal travel itinerary. They give airlines access to key information about your contact information and reservation—even your meal preferences. This is why it's ill-advised to post a photo of your boarding pass to social media while waiting at your airport gate. A hacker could theoretically use that PNR to access your account, and from there they could claim your frequent flier miles, change your flight details, or cancel your trip altogether.

You might also see a random standalone letter on your boarding pass. This references your booking class. "A" and "F," for instance, are typically used for first-class seats. The letter "Y" generally stands for economy class, while "Q" is an economy ticket purchased at a discounted rate. If you see a "B" you might be in luck—it means you could be eligible for a seat upgrade.

There might be other letters, too. "S/O," which is short for stopover, means you have a layover that lasts longer than four hours in the U.S. or more than 24 hours in another country. Likewise, "STPC" means "stopover paid by carrier," so you'll likely be put up in a hotel free of charge. Score!

One code you probably don’t want to see is "SSSS," which means your chances of getting stopped by TSA agents for a "Secondary Security Screening Selection" are high. For whatever reason, you've been identified as a higher security risk. This could be because you've booked last-minute or international one-way flights, or perhaps you've traveled to a "high-risk country." It could also be completely random.

Still confused? For a visual of what that all these codes look like on a boarding pass, check out this helpful infographic published by Lifehacker.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

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